Generally, an automotive air conditioner is provided with an air duct which has air inlet openings and air outlet openings, and includes heat exchangers with a plurality of damper elements to control the temperature and passageway of the air.
With reference to FIG. 1, a conventional structure of an automotive air conditioner is shown.
Air duct 1 has air inlet opening 2 which communicates with an external space and compartment of the automobile through a recirculated air inlet (not shown). Air duct 1 also has a plurality of outlets, such as upper outlet 3, lower outlet 4 and defroster outlet 5 each of which opens into the compartment. The air is drawn through the air duct 1 from air inlet 2, and flows out into the automobile compartment from upper outlet 3, lower outlet 4 and defroster outlet 5. Normally, is air circulation is forced by blower device 6 disposed in the air inlet side of duct 1.
Evaporator 7 which is a part of a refrigerant circuit is disposed in air duct 1 for cooling air passing therethrough. Heater core 8 is also disposed in air duct 1, down stream from evaporator 7, to divide the passageway of duct 1 into two ways. That is heater core 8 is placed so as to partly cover the passageway of duct 1 so as to form a bypass way 10 in the duct. Thus, a passage to pass through cooled air is provided. The rear side space of heater core 8 functions as an air mixture chamber 14, because, in the mixture chamber 14, the air passed through heater core 8 and air passed through bypass way 10 are mixed with one another to control the temperature of air flow out into the automobile compartment through one of the outlets. Air inflow volume through heater core 8 and bypass passage 10 should be controlled by a first damper 9 disposed on the front side of heater core 8. The opening and closing of upper outlet 3 is controlled by a second damper 11. The opening and closing of lower outlet 4 is controlled by a third damper 12. Also, the opening and closing of defroster outlet 5 is controlled by a fourth damper 13.
In the above-mentioned automotive air conditioning system, during the bi-level mode, i.e., when cool air is flowing out from upper outlet 3 and warm air is flowing out from lower outlet 4, the out flow of air from upper and lower outlets 3 and 4 is normally a mixture of both cooled and warm air. This is because, second damper 11 is not disposed in duct 1 to divide the mixture within chamber 14 into two chambers when second damper 11 is positioned to open the upper outlet 3. Therefore, in the bi-level mode, the flow ways of cooled air and warm air are not clearly divided from one another. As a result of this structure, the temperature differential between cool air flowing into upper outlet 3 and warm air flowing into lower outlet 4 becomes small.
One solution to resolve the above-mentioned disadvantage is to clearly divide the mixture chamber into two chambers when the air conditioner is operated at the bi-level mode. As shown in FIG. 2, partition wall 31 of upper outlet 3 could be extended into mixture chamber 14 to divide chamber 14 into two chambers due to operation of second damper 11. In this structure of the air conditioner, if the air conditioner is operated in the bi-level mode, cooled air passes through by-pass passage 10 and warm air passes through heater core 8, flowing in separate ways, and not mixed with one another. Therefore, the temperature differential between cool air passing through upper outlet 3 and warm air passing through lower outlet 4 is too large. However, if the air conditioner is operated in the cooling mode, second damper 11 opens upper outlet 3 and divides the mixture in chamber 14 into two chambers. That is, cooled air passes through by-pass passage 10 to directly flow out of the compartment through upper outlet 3 and is not mixed with warm air passed through heater core 8. Therefore, the temperature of the air flowing into the automobile compartment can not be controlled by mixture of cooled and warm air. The temperature of the air needs to be controlled by a thermostat.